Tuberculosis is the second-most common cause of mortality from an infectious disease in the world, killing nearly three people every minute.

While it is generally a curable disease—it first must be diagnosed, and that has been one of the biggest barriers in its elimination. M. tuberculosis grows slowly, so traditional methods of diagnostic testing and determining if treatments are working both take a very long time.

Now, a new method, reported in PLOS ONE, is able to detect whether a potential treatment is working as early as a day after it is given.

“Since M. tuberculosis takes about a month to quantify using traditional approaches, any method that allows direct determination of the amount of bacteria present is very valuable and speeds progress, saving months every time an experiment is done,” says Jeffrey Cirillo, a professor at the Texas A&M Health Science Center. “Our methods allow this.”

Cirillo’s previous research has focused on developing a rapid yet inexpensive test for tuberculosis. He and colleagues have nearly perfected the technology and are in the process of bringing the test to market.

Using optical imaging technology, the researchers can observe the bacteria in real time, in living animals, without harming them. This way, it is easy to determine if a proposed treatment is working and the number of bacteria is decreasing.

“There have never been sensitive enough systems to measure the bacteria directly in animals,” Cirillo says. “This is a completely new technology and has nearly limitless applications to microbiological research, particularly in animals, but it increases sensitivity in any experimental system.”

Drug-resistant tuberculosis, now present everywhere in the world, is hampering efforts to fight the disease because the usual drugs used to treat it are no longer effective. Therefore, new, more effective treatments need to be developed.

The researchers first had to find the best fluorescent protein to help them visualize the bacteria.

“We use very sensitive systems that can actually see the signal through mammalian tissue,” Cirillo says. “This works best in the near-infrared, which is where our signals are primarily produced.”

Active TB causes symptoms such as cough, fever, night sweats, and weight loss. If left untreated—a common scenario in developing countries lacking health care infrastructure—a person with active TB has only a 50 percent chance of survival, can infect an average of 10 to 15 people each year.

“The goal in TB research is complete eradication of the disease,” Cirillo says. “We think this new technology is one tool to do just that.”